U.S. patent application number 10/864310 was filed with the patent office on 2005-12-15 for hydrogen sulfide scrubber using polymeric amine and associated methods.
This patent application is currently assigned to Precision Control Technology, Inc.. Invention is credited to Cheshire, James E., Davis, Jerry M..
Application Number | 20050274256 10/864310 |
Document ID | / |
Family ID | 35459159 |
Filed Date | 2005-12-15 |
United States Patent
Application |
20050274256 |
Kind Code |
A1 |
Davis, Jerry M. ; et
al. |
December 15, 2005 |
Hydrogen sulfide scrubber using polymeric amine and associated
methods
Abstract
A hydrogen sulfide scrubber includes first and second scrubber
tanks with scrubber media contained therein. Scrubbing solution
circulators each include a dispenser for dispensing scrubbing
solution into contact with the scrubber media, a sump for
collecting the scrubbing solution after contact with the scrubber
media, and a circulating pump for circulating the scrubbing
solution from the sump back to the dispenser after contact with the
scrubber media. A polymeric amine supply is provided for supplying
a polymeric amine to the scrubbing solution in the second tank. The
scrubbing solution in the first tank may be charged with the
polymeric amine by a charging line extending from the second tank
to the first tank. In other embodiments, a regenerative blower and
associated nozzle may be used to generate a scrubbing solution mist
in the space beneath the scrubber media and above the sump.
Inventors: |
Davis, Jerry M.; (Okahumpka,
FL) ; Cheshire, James E.; (Tavares, FL) |
Correspondence
Address: |
CHRISTOPHER F. REGAN, ESQUIRE
ALLEN, DYER, DOPPELT, MILBRATH & GILCHRIST, P.A.
P.O. Box 3791
Orlando
FL
32802-3791
US
|
Assignee: |
Precision Control Technology,
Inc.
Tavares
FL
|
Family ID: |
35459159 |
Appl. No.: |
10/864310 |
Filed: |
June 9, 2004 |
Current U.S.
Class: |
95/199 ;
95/235 |
Current CPC
Class: |
B01D 53/1468 20130101;
B01D 53/1493 20130101 |
Class at
Publication: |
095/199 ;
095/235 |
International
Class: |
B01D 053/14 |
Claims
That which is claimed is:
1. A hydrogen sulfide scrubber comprising: a first scrubber tank
and first scrubber media contained therein, said first scrubber
tank having a gas flow inlet to receive a hydrogen
sulfide-containing gas flow and a gas flow outlet; a second
scrubber tank and second scrubber media contained therein, said
second scrubber tank having a gas flow inlet connected downstream
from the gas flow outlet of said first scrubber tank; a first
scrubbing solution circulator comprising a first dispenser for
dispensing a first scrubbing solution into contact with said first
scrubber media, a first sump for collecting the first scrubbing
solution after contact with said first scrubber media, and a first
circulating pump for circulating the first scrubbing solution from
said first sump back to said first dispenser after contact with
said first scrubber media; a second scrubbing solution circulator
comprising a second dispenser for dispensing a second scrubbing
solution into contact with said second scrubber media, a second
sump for collecting the second scrubbing solution after contact
with said second scrubber media, and a second circulating pump for
circulating the second scrubbing solution from said second sump
back to said second dispenser after contact with said second
scrubber media; a polymeric amine supply connected to said second
scrubbing solution circulator; and a scrubbing solution charging
line for supplying a portion of the second scrubbing solution to
the first scrubbing solution to charge the first scrubbing solution
with the polymeric amine.
2. A hydrogen sulfide scrubber according to claim 1 further
comprising a controller for controlling said polymeric amine
supply.
3. A hydrogen sulfide scrubber according to claim 2 further
comprising at least one hydrogen sulfide sensor connected to said
controller; and wherein said controller controls said polymeric
amine supply based upon said at least one hydrogen sulfide
sensor.
4. A hydrogen sulfide scrubber according to claim 3 wherein said at
least one hydrogen sulfide sensor comprises an inlet gas sensor
including: a first sampling tube having a first inlet connected in
fluid communication with the hydrogen sulfide-containing gas flow
to said first scrubber tank, and a first outlet; a first hydrogen
sulfide sensing device connected to the first outlet; a first purge
pump connected to said first sampling tube adjacent the first
outlet; and a first condensation drain valve connected to said
first sampling tube.
5. A hydrogen sulfide scrubber according to claim 4 wherein said
controller periodically operates said first purge pump and said
first condensation drain valve.
6. A hydrogen sulfide scrubber according to claim 3 wherein said at
least one hydrogen sulfide sensor comprises a discharge gas sensor
including: a second sampling tube having a second inlet connected
in fluid communication with a discharge gas flow from said second
scrubber tank, and a second outlet; a second hydrogen sulfide
sensing device connected to the second outlet; a second purge pump
connected to said second sampling tube adjacent the second outlet;
and a second condensation drain valve connected to said second
sampling tube.
7. A hydrogen sulfide scrubber according to claim 6 wherein said
controller periodically operates said second purge pump and said
second condensation drain valve.
8. A hydrogen sulfide scrubber according to claim 1 further
comprising a make-up water supply connected to at least one of said
first and second scrubbing solution circulators.
9. A hydrogen sulfide scrubber according to claim 1 further
comprising: a caustic supply; and a switchover valve arrangement
for permitting selective alternate operation using said caustic
supply or said polymeric amine supply.
10. A hydrogen sulfide scrubber according to claim 1 wherein said
polymeric amine comprises SULFA-CLEAR.RTM..
11. A hydrogen sulfide scrubber according to claim 1 further
comprising a regenerative blower and a nozzle connected thereto for
generating a scrubbing solution mist in said first scrubber
tank.
12. A hydrogen sulfide scrubber according to claim 11 wherein said
first scrubber tank has a first space above said first sump and
beneath said first scrubber media; and wherein said regenerative
blower and said nozzle generate the scrubbing solution mist in the
first space.
13. A hydrogen sulfide scrubber according to claim 11 wherein said
nozzle comprises a venturi injector nozzle.
14. A hydrogen sulfide scrubber comprising: a first scrubber tank
and first scrubber media contained therein, said first scrubber
tank having a gas flow inlet to receive a hydrogen
sulfide-containing gas flow and a gas flow outlet; a second
scrubber tank and second scrubber media contained therein, said
second scrubber tank having a gas flow inlet connected downstream
from the gas flow outlet of said first scrubber tank; a first
scrubbing solution circulator comprising a first dispenser for
dispensing a first scrubbing solution into contact with said first
scrubber media, a first sump for collecting the first scrubbing
solution after contact with said first scrubber media, and a first
circulating pump for circulating the first scrubbing solution from
said first sump back to said first dispenser after contact with
said first scrubber media; a second scrubbing solution circulator
comprising a second dispenser for dispensing a second scrubbing
solution into contact with said second scrubber media, a second
sump for collecting the second scrubbing solution after contact
with said second scrubber media, and a second circulating pump for
circulating the second scrubbing solution from said second sump
back to said second dispenser after contact with said second
scrubber media; a polymeric amine supply connected to at least one
of said first and second scrubbing solution circulators; and a
regenerative blower and a nozzle connected thereto for generating a
scrubbing solution mist in at least one of said first and second
scrubber tanks.
15. A hydrogen sulfide scrubber according to claim 14 wherein said
first scrubber tank has a first space above said first sump and
beneath said first scrubber media; and wherein said regenerative
blower and said nozzle generate the scrubbing solution mist in the
first space.
16. A hydrogen sulfide scrubber according to claim 14 wherein said
nozzle comprises a venturi injector nozzle.
17. A hydrogen sulfide scrubber according to claim 16 further
comprising a controller for controlling said polymeric amine
supply.
18. A hydrogen sulfide scrubber according to claim 17 further
comprising at least one hydrogen sulfide sensor connected to said
controller; and wherein said controller controls said polymeric
amine supply based upon said at least one hydrogen sulfide
sensor.
19. A hydrogen sulfide scrubber according to claim 18 wherein said
at least one hydrogen sulfide sensor comprises an inlet gas sensor
including: a first sampling tube having a first inlet connected in
fluid communication with the hydrogen sulfide-containing gas flow
to said first scrubber tank, and a first outlet; a first hydrogen
sulfide sensing device connected to the first outlet; a first purge
pump connected to said first sampling tube adjacent the first
outlet; and a first condensation drain valve connected to said
first sampling tube.
20. A hydrogen sulfide scrubber according to claim 19 wherein said
controller periodically operates said first purge pump and said
first condensation drain valve.
21. A hydrogen sulfide scrubber according to claim 18 wherein said
at least one hydrogen sulfide sensor comprises a discharge gas
sensor including: a second sampling tube having a second inlet
connected in fluid communication with a discharge gas flow from
said second scrubber tank, and a second outlet; a second hydrogen
sulfide sensing device connected to the second outlet; a second
purge pump connected to said second sampling tube adjacent the
second outlet; and a second condensation drain valve connected to
said second sampling tube.
22. A hydrogen sulfide scrubber according to claim 21 wherein said
controller periodically operates said second purge pump and said
second condensation drain valve.
23. A hydrogen sulfide scrubber according to claim 14 further
comprising a make-up water supply connected to at least one of said
first and second scrubbing solution circulators.
24. A hydrogen sulfide scrubber according to claim 14 further
comprising: a caustic supply; and a switchover valve arrangement
for permitting selective alternate operation using said caustic
supply or said polymeric amine supply.
25. A hydrogen sulfide scrubber according to claim 14 wherein said
polymeric amine comprises SULFA-CLEAR.RTM..
26. A hydrogen sulfide scrubber comprising: a scrubber tank and
scrubber media contained therein; a scrubbing solution circulator
comprising a dispenser for dispensing a scrubbing solution into
contact with said scrubber media, a sump for collecting the
scrubbing solution after contact with said scrubber media, and a
circulating pump for circulating the scrubbing solution from said
sump back to said dispenser after contact with said scrubber media;
a polymeric amine supply connected to said scrubbing solution
circulator; and a regenerative blower and a nozzle connected
thereto for generating a scrubbing solution mist in said scrubber
tank.
27. A hydrogen sulfide scrubber according to claim 26 wherein said
scrubber tank has a space above said sump and beneath said scrubber
media; and wherein said regenerative blower and said nozzle
generate the scrubbing solution mist in the space.
28. A hydrogen sulfide scrubber according to claim 26 wherein said
nozzle comprises a venturi injector nozzle.
29. A hydrogen sulfide scrubber according to claim 26 further
comprising a controller for controlling said polymeric amine
supply.
30. A hydrogen sulfide scrubber according to claim 29 further
comprising at least one hydrogen sulfide sensor connected to said
controller; and wherein said controller controls said polymeric
amine supply based upon said at least one hydrogen sulfide
sensor.
31. A hydrogen sulfide scrubber according to claim 26 further
comprising a make-up water supply connected to said scrubbing
solution circulator.
32. A hydrogen sulfide scrubber according to claim 26 wherein said
polymeric amine comprises SULFA-CLEAR.RTM..
33. A method for hydrogen sulfide scrubbing comprising: using a
first scrubber tank and first scrubber media contained therein by
operating a first scrubbing solution circulator comprising a first
dispenser dispensing a first scrubbing solution into contact with
the first scrubber media, a first sump collecting the first
scrubbing solution after contact with the first scrubber media, and
a first circulating pump circulating the first scrubbing solution
from the first sump back to the first dispenser after contact with
the first scrubber media; using a second scrubber tank and second
scrubber media contained therein downstream from the first scrubber
tank by operating a second scrubbing solution circulator comprising
a second dispenser dispensing a second scrubbing solution into
contact with the second scrubber media, a second sump collecting
the second scrubbing solution after contact with the second
scrubber media, and a second circulating pump circulating the
second scrubbing solution from the second sump back to the second
dispenser after contact with the second scrubber media; supplying a
polymeric amine to the second scrubbing solution circulator; and
supplying a portion of the second scrubbing solution to the first
scrubbing solution via a charging line to charge the first
scrubbing solution with the polymeric amine.
34. A method according to claim 33 further comprising controlling
supplying the polymeric amine using a controller.
35. A method according to claim 34 further comprising controlling
based upon at least one hydrogen sulfide sensor.
36. A method according to claim 35 wherein the at least one
hydrogen sulfide sensor comprises an inlet gas sensor.
37. A method according to claim 35 wherein the at least one
hydrogen sulfide sensor comprises an outlet gas sensor.
38. A method according to claim 33 further comprising adding
make-up water to at least one of the first and second scrubbing
solutions.
39. A method according to claim 33 further comprising permitting
selective alternate operation using a caustic or the polymeric
amine.
40. A method according to claim 33 wherein the polymeric amine
comprises SULFA-CLEAR.RTM..
41. A method according to claim 33 further comprising generating a
scrubbing solution mist in at least one of the first and second
scrubber tanks using a regenerative blower and a nozzle connected
thereto.
42. A method according to claim 41 wherein the first scrubber tank
has a first space above the first sump and beneath the first
scrubber media; and wherein the scrubbing solution mist is
generated in the first space.
43. A method for hydrogen sulfide scrubbing comprising: using a
scrubber tank and scrubber media contained therein by operating a
scrubbing solution circulator comprising a dispenser dispensing a
scrubbing solution into contact with the scrubber media, a sump
collecting the scrubbing solution after contact with the scrubber
media, and a circulating pump circulating the scrubbing solution
from the sump back to the dispenser after contact with the scrubber
media; supplying a polymeric amine to the scrubbing solution
circulator; and generating a scrubbing solution mist in the
scrubber tank using a regenerative blower and a nozzle connected
thereto.
44. A method according to claim 43 wherein the scrubber tank has a
first space above the sump and beneath the scrubber media; and
wherein the scrubbing solution mist is generated in the space.
45. A method according to claim 43 wherein the nozzle comprises a
venturi injector nozzle.
46. A method according to claim 43 further comprising controlling
supplying the polymeric amine using a controller.
47. A method according to claim 46 further comprising controlling
based upon at least one hydrogen sulfide sensor.
48. A method according to claim 47 wherein the at least one
hydrogen sulfide sensor comprises an inlet gas sensor.
49. A method according to claim 47 wherein the at least one
hydrogen sulfide sensor comprises an outlet gas sensor.
50. A method according to claim 43 further comprising adding
make-up water to the scrubbing solution.
51. A method according to claim 43 further comprising permitting
selective alternate operation using a caustic or the polymeric
amine supply.
52. A method according to claim 43 wherein the polymeric amine
comprises SULFA-CLEAR.RTM..
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of drinking water
treatment and, more particularly, to the field of hydrogen sulfide
scrubbing in a drinking water treatment system.
BACKGROUND OF THE INVENTION
[0002] Drinking water is typically extracted from an aquifer and
processed in a water treatment system to remove undesired
contaminants and impurities, and add a sanitizer, such as chlorine,
for example. Water taken from an aquifer may contain a high
hydrogen sulfide content, because of surrounding geological
features and/or the action of certain bacteria. Unfortunately,
hydrogen sulfide gas has an unpleasant odor and it is undesirable
to discharge into the atmosphere that can then annoy residents of
surrounding neighborhoods, for example.
[0003] Some water treatment plants remove or scrub hydrogen sulfide
from the water with a caustic scrubbing solution, such as including
potassium hydroxide or sodium hydroxide. In such a system, water
pumped from the aquifer is first passed through an aerator for
extracting a hydrogen sulfide-containing gas flow from the water.
The hydrogen sulfide-containing gas flow is then passed through a
hydrogen sulfide scrubber including at least one scrubber tank
through which the caustic scrubbing solution is circulated and
constantly replenished.
[0004] A common configuration of a hydrogen sulfide scrubber
includes two scrubber tanks each having generally lightweight
scrubber media therein. The scrubber tanks may be as offered by the
Duall Division of Met-Pro Corporation of Owosso, Mich. under the
model series designation PT-500. The scrubber media may be in the
form of hollow spheres with passageways therein to provide a large
surface area to enhance the capture of hydrogen sulfide from the
gas flow and into the scrubbing solution. The hydrogen sulfide
scrubber may also include first and second scrubbing solution
circulators, each dispensing a scrubbing solution into contact with
the scrubber media, a sump for collecting the scrubbing solution,
and a circulating pump for circulating the scrubbing solution from
the sump and back to the dispenser. The scrubbing solution includes
caustic to adjust the pH to a desired level at which the hydrogen
sulfide will more readily dissolve into the scrubbing solution.
[0005] The caustic material, however, causes a build-up in the
scrubber tank, and especially on the scrubber media. This build-up
covers and may block the passageways in the scrubber media and
reduce the available surface area for extracting the hydrogen
sulfide. The build-up also increases the weight of the scrubber
media and reduces movement during scrubbing. Moreover, the
increased weight may also stress the supporting structure of the
tank.
[0006] Periodic cleaning is recommended for caustic-based hydrogen
sulfide scrubbers. Such cleaning is generally performed by acid
washing and is relatively difficult. Accordingly, maintenance may
be postponed until the removal of hydrogen sulfide is no longer
acceptable. At this point, very costly replacement of the scrubber
media may be needed. The use of caustic further requires careful
handling, and is relatively expensive when the cost of removing the
build-up is considered. The use of caustic also requires a
considerable flow of make-up water and a corresponding relatively
large discharge of spent scrubber solution into the sewer
system.
[0007] A significant advance in the area of hydrogen sulfide
removal, while reducing build-up in the scrubber, is the use of
triazine compound in the scrubber solution as disclosed in
published U.S. patent application Ser. No. 2004/0055463 assigned to
the present assignee. Despite the improvement offered by the use of
the triazine compound versus traditional caustic scrubbing
solutions, other odor causing compounds may still be released, such
as volatile mercaptans. The mercaptans may cause an undesirable
odor in the vicinity of the scrubber. Of course, there is also a
continuing desire to increase hydrogen sulfide removal and reduce
build-up on the scrubbing media.
SUMMARY OF THE INVENTION
[0008] In view of the foregoing background, it is therefore an
object of the present invention to provide a cost effective and
relatively straightforward process to treat hydrogen sulfide in a
drinking water system while reducing build-up and the need for
maintenance, and also while reducing the release of volatile
mercaptans.
[0009] These and other objects, features and advantages in
accordance with the invention are provided by a hydrogen sulfide
scrubber comprising first and second scrubber tanks, a polymeric
amine supply connected to a second scrubbing solution circulator
for the second scrubber tank, and a scrubbing solution charging
line for supplying a portion of a second scrubbing solution to a
first scrubbing solution in the first scrubber tank to charge the
first scrubbing solution with the polymeric amine. The hydrogen
sulfide scrubber may be used for drinking water treatment or
wastewater treatment, for example. The use of the polymeric amine
reduces volatile mercaptans to thereby reduce undesired odors. In
addition, the charging line provides efficient and cost effective
use of the polymeric amine. The polymeric amine also effectively
reduces the hydrogen sulfide content without causing extensive
build-up within the tank and on the media.
[0010] The first scrubber tank may contain first scrubber media
therein, and may have a gas flow inlet to receive a hydrogen
sulfide-containing gas flow and a gas flow outlet. The second
scrubber tank may contain a second scrubber media therein, and may
have a gas flow inlet connected downstream from the gas flow outlet
of the first scrubber tank. The scrubber may include a first
scrubbing solution circulator that includes a first dispenser for
dispensing the first scrubbing solution into contact with the first
scrubber media, a first sump for collecting the first scrubbing
solution after contact with the first scrubber media, and a first
circulating pump for circulating the first scrubbing solution from
the first sump back to the first dispenser after contact with the
first scrubber media. Similarly, the scrubber may also include a
second scrubbing solution circulator comprising a second dispenser
for dispensing a second scrubbing solution into contact with the
second scrubber media, a second sump for collecting the second
scrubbing solution after contact with the second scrubber media,
and a second circulating pump for circulating the second scrubbing
solution from the second sump back to the second dispenser after
contact with the second scrubber media. In other words, the
scrubber may be at least a two-stage scrubber.
[0011] The scrubber may also include a controller for controlling
the polymeric amine supply based upon hydrogen sulfide sensors
associated with the first and second scrubber tanks. In particular,
the hydrogen sulfide sensors may comprise an inlet gas sensor that
includes a sampling tube having an inlet connected in fluid
communication with the hydrogen sulfide-containing gas flow to the
first scrubber tank. The hydrogen sulfide sensor may also include a
hydrogen sulfide sensing device connected to the outlet of the
sampling tube. A purge pump may be connected to the sampling tube
adjacent the outlet thereof. A condensation drain valve may also be
connected to the sampling tube to drain accumulated condensation
from within the sampling tube. The controller may periodically
operate the purge pump and the condensation drain valve to enhance
the accuracy of the readings.
[0012] The sensor, purge pump, and drain valve may be positioned
within a housing of the controller. A similar outlet gas sensor may
also be provided which includes a sampling tube having an inlet
connected in fluid communication with a discharge gas flow from the
second scrubber tank, for example.
[0013] The scrubber may further comprise a make-up water supply
connected to at least one of the first and second scrubbing
solution circulators. In some embodiments, the hydrogen sulfide
scrubber may further comprise a caustic supply and a switchover
valve arrangement for permitting selective alternate operation
using the caustic supply or the polymeric amine supply. This
permits a scrubber to be operated using either scrubbing solution
chemistry.
[0014] The hydrogen sulfide scrubber may further include a
regenerative blower and an associated nozzle for generating a
scrubbing solution mist in at least one of the first and second
scrubber tanks. The scrubbing solution mist comprising the
polymeric amine may be especially helpful in removing a significant
portion of the hydrogen sulfide and any volatile mercaptans, for
example. The first scrubber tank may have a first space above the
first sump and beneath the first scrubber media, and the
regenerative blower and nozzle may generate the scrubbing solution
mist in the first space. The nozzle may be a venturi injector
nozzle, for example. This regenerative blower and nozzle to
generate a mist of the scrubbing solution may be used in the
multi-stage scrubber, or even a single stage scrubber that does not
include the charging line as discussed above.
[0015] A method aspect in accordance with the invention is for
hydrogen sulfide scrubbing. The method may include using a first
scrubber tank and first scrubber media contained therein by
operating a first scrubbing solution circulator comprising a first
dispenser dispensing a first scrubbing solution into contact with
the first scrubber media, a first sump collecting the first
scrubbing solution after contact with the first scrubber media, and
a first circulating pump circulating the first scrubbing solution
from the first sump back to the first dispenser after contact with
the first scrubber media. The method may also include using a
second scrubber tank and second scrubber media contained therein
downstream from the first scrubber tank by operating a second
scrubbing solution circulator comprising a second dispenser
dispensing a second scrubbing solution into contact with the second
scrubber media, a second sump collecting the second scrubbing
solution after contact with the second scrubber media, and a second
circulating pump circulating the second scrubbing solution from the
second sump back to the second dispenser after contact with the
second scrubber media. Moreover, the method may include supplying a
polymeric amine to the second scrubbing solution circulator, and
supplying a portion of the second scrubbing solution to the first
scrubbing solution via a charging line to charge the first
scrubbing solution with the polymeric amine.
[0016] Another method aspect of the invention is also for hydrogen
sulfide scrubbing. This method may include using a scrubber tank
and scrubber media contained therein by operating a scrubbing
solution circulator comprising a dispenser dispensing a scrubbing
solution into contact with the scrubber media, a sump collecting
the scrubbing solution after contact with the scrubber media, and a
circulating pump circulating the scrubbing solution from the sump
back to the dispenser after contact with the scrubber media.
Moreover, the method may also include supplying a polymeric amine
to the scrubbing solution circulator, and generating a scrubbing
solution mist in the scrubber tank. The scrubbing solution mist may
be generated using a regenerative blower and associated nozzle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a schematic diagram of a water treatment system
including an embodiment of the hydrogen sulfide scrubber according
to the present invention.
[0018] FIG. 2 is a more detailed schematic diagram of the hydrogen
sulfide scrubber and controller as shown in FIG. 1.
[0019] FIG. 3 is a more detailed schematic diagram of the
controller and hydrogen sulfide sensors as shown in FIG. 2.
[0020] FIG. 4 is a schematic diagram of another embodiment of a
hydrogen sulfide scrubber as shown in FIG. 2, but having both
caustic and polymeric amine supplies.
[0021] FIG. 5 is a schematic diagram of still another embodiment of
the hydrogen sulfide scrubber according to the present
invention.
[0022] FIG. 6 is a more detailed schematic cross-sectional view of
the regenerative blower and associated venturi injector nozzle as
shown in FIG. 5.
[0023] FIG. 7 is a flow chart illustrating a method of scrubbing
hydrogen sulfide according to the present invention.
[0024] FIG. 8 is a flow chart illustrating a method of retrofitting
a hydrogen sulfide scrubber according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings, in which
preferred embodiments of the invention are shown. This invention
may, however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein. Rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. Like numbers refer to like
elements throughout, and prime and double prime notation are used
to indicate similar elements in alternate embodiments
[0026] Referring initially to FIGS. 1 and 2, a drinking water
treatment system 10 is now described. The drinking water treatment
system 10 illustratively includes a pump 15 for pumping water from
an aquifer 17 that is below ground level. For example, the aquifer
17 may be between 100 and 1000 feet below ground level.
[0027] The drinking water treatment system 10 also illustratively
comprises an aerator 18 downstream from the pump 15 for generating
an outlet water flow 20 and a hydrogen sulfide-containing gas flow
22 by extracting hydrogen sulfide from the water. A sanitizer 30
for sanitizing the outlet water flow 20 is connected downstream
from the aerator 18 to make drinking water. The sanitizer 30 may,
for example, be provided by a chlorinator, ultra-violet light
exposure, or other sanitizing processes as understood by those
skilled in the art. Depending on the needs of the community, the
drinking water treatment system 10 may include a storage facility
32 for storing the sanitized water before it is dispensed to the
community through a water distribution system 34. Of course, the
drinking water treatment system 10 may include processing stages
that have been omitted for clarity as needed to treat water in
different communities, e.g., fluorination and filtration, as
understood by those skilled in the art.
[0028] The drinking water treatment system 10 further
illustratively comprises a hydrogen sulfide scrubber 40 for
scrubbing the hydrogen sulfide-containing gas flow 22 from the
aerator 18. Referring more particularly to FIG. 2, the hydrogen
sulfide scrubber 40 includes a first scrubber tank 42a and a second
scrubber tank 42b.
[0029] The first scrubber tank 42a illustratively includes a gas
flow inlet 43 connected to the aerator 18 to receive the hydrogen
sulfide-containing gas flow 22 therefrom. A gas flow outlet 47 is
illustratively included at an upper portion of the first scrubber
tank 42a. The second scrubber tank 42b illustratively includes a
gas flow inlet 45 connected to the gas flow outlet 47 of the first
scrubber tank 42a via a gas flow line 49. The second scrubber tank
42b further includes a gas flow outlet 48 at an upper portion
thereof from which the treated gas flow is discharged to the
atmosphere.
[0030] Scrubber media 46a, 46b are illustratively contained within
the first and second scrubber tanks 42a, 42b. The scrubber media
46a, 46b may, for example, be provided by generally lightweight and
hollow spheres made of polypropylene material. Such spheres are
available from Tri-Pac of Raleigh, N.C. under the trade name
Tri-Packs.RTM.. Other scrubbing media is also contemplated by the
present invention.
[0031] The hydrogen sulfide scrubber 40 further illustratively
comprises first and second scrubbing solution circulators 50a, 50b
connected to each of the first and second scrubber tanks 42a, 42b.
The first scrubbing solution circulator 50a uses a first scrubbing
solution 53a and the second scrubbing solution circulator 50b uses
a second scrubbing solution 53b.
[0032] The scrubbing solution circulators 50a, 50b include
dispensers 52a, 52b for dispensing the first and second scrubbing
solutions 53a, 53b into contact with the scrubber media 46a, 46b.
The scrubbing solution circulators 50a, 50b also include sumps 56a,
56b for collecting the first and second scrubbing solutions 53a,
53b after contact with the scrubber media 46a, 46b, and circulating
pumps 58a, 58b for circulating the first and second scrubbing
solutions from the sumps back to the dispensers 52a, 52b after
contact with the scrubber media. The scrubbing solution circulators
50a, 50b include circulator lines 55a, 55b connected between the
sump 56a, 56b and the dispensers 52a, 52b. The circulating pumps
58a, 58b may be connected to the circulator lines 55a, 55b to
circulate the first and second scrubbing solutions 53a, 53b from
the sumps 56a, 56b to the dispensers 52a, 52b.
[0033] The drinking water treatment system 10 is but one example of
the use of the hydrogen sulfide scrubber 40 in accordance with the
present invention. For example, the hydrogen sulfide scrubber 40
could also be used for treating hydrogen sulfide-containing gas
from wastewater. Other applications of the hydrogen sulfide
scrubber 40 will be readily understood by those skilled in the
art.
[0034] The hydrogen sulfide scrubber 40 further illustratively
comprises a polymeric amine compound supply 60 for supplying a
polymeric amine reagent 62 to the second scrubbing solution 53b.
The polymeric amine 62 captures the hydrogen sulfide into the
scrubber solution 53a, 53b, as well as mercaptans.
[0035] For example, Weatherford of Houston, Tex. offers a line of
chemicals under the designation SULFA-CLEAR.RTM. to remove nuisance
hydrogen sulfide from natural gas, crude oil, LPG, NGL, waster
water, ground water, and aqueous systems. SULFA-CLEAR.RTM. is
formulated for absorption hydrogen sulfide and volatile mercaptans.
The combination of multiple amine sites and organophilic properties
allows for fast, efficient abatement of these problem compounds.
SULFA-CLEAR.RTM. absorbs and reacts with the hydrogen sulfide and
mercaptans to form water-soluble and non-volatile poly sulfides
that are readily consumed in the downstream waste treatment
process. The spent reaction products may also help reduce
corrosion. The chemical composition and properties of
SULFA-CLEAR.RTM. are further described in U.S. Pat. No. 5,488,103,
the entire contents of which are incorporated herein by reference.
Applicants have also found that the particular polymeric amine
reagent identified as SULFA-CLEAR.RTM. 5167 may be especially
useful, although other similar products are also contemplated by
the present invention.
[0036] In its associated marketing literature, Weatherford
discloses that maximization of contact is the important physical
component for efficient removal of hydrogen sulfide. The chemical
reagent should partition to where the hydrogen sulfide resides in
the gas, hydrocarbon liquid, or water. Liquid scavengers are
identified as the most effective and versatile reagents, and can be
used with chemical injection systems incorporating multiple
injection points, atomizers, static mixers, downstream separators,
wet scrubbers, drip feed systems, and vapor phase scrubbers for
spent product separation and removal. They can also be used in
bubble towers and absorption towers for maximum intimacy of liquid
droplets with gas molecules.
[0037] Returning now again to FIG. 2, a supply pump 64 may be
connected to the polymeric amine supply 60 to pump the polymeric
amine reagent 62 from a storage container 66 to the second
scrubbing solution circulator 50b. A line 68 illustratively extends
between the storage container 66 and the second scrubber tank 42b
to deliver the polymeric amine 62 to the second scrubbing solution
53b. The polymeric amine supply 60 is illustratively supplied to
only the second scrubbing solution circulator 50b.
[0038] The hydrogen sulfide scrubber 40 further illustratively
comprises a scrubbing solution charging line 70 for supplying a
portion of the second scrubbing solution 53b to the first scrubbing
solution 53a to charge the first scrubbing solution with the
polymeric amine 62. The scrubbing solution charging line 70 is
illustratively connected between the first scrubber tank 42a and
second scrubber tank 42b. A charging line pump 72 is connected to
the scrubber solution charging line 70 to pump a portion of the
second scrubbing solution 53b from the sump 56b of the second
scrubber tank 42b to the sump 56a of the first scrubber tank 42a.
The pump 72 may not be needed in other embodiments, such as where
the scrubbing solution is diverted from the pressure side of the
circulating pump 58b, for example.
[0039] A make-up water supply 24a, 24b is illustratively connected
to the each of the first and second scrubber tanks 42a, 42b to
supply make-up water to the first and second scrubbing solutions
53a, 53b. When supplying the polymeric amine 62 to the second
scrubber tank 42, make-up water may only be supplied to the second
scrubber tank under normal operating conditions. The second make-up
water supply 24b may supply make-up water at a desired rate
depending on the size of the scrubber tanks 42a, 42b, e.g., 6
gallons per minute (gpm). Accordingly, the scrubbing solution
charging line 70 may supply the first scrubbing solution 53a with a
portion of the second scrubbing solution 53b at a substantially
similar rate. Further, when supplying the polymeric amine 62 to the
second scrubbing solution 53b, the make-up water supply 24a of the
first scrubber tank 42a may be turned off at the first make-up
water valve 25a, while the second make-up water valve 25b is set to
6 gpm, for example. The first and second scrubber tanks 42a, 42b
may further illustratively include overflow lines 28a, 28b for
maintaining the first and second scrubbing solutions 53a, 53b at
desired levels within the sumps 56a, 56b.
[0040] Turning now additionally to FIG. 3, a controller 80 for
controlling the polymeric amine supply 60 is now described in more
detail. The controller 80 is illustratively connected to the supply
pump 64 to regulate the amount of polymeric amine 62 to be supplied
to the second scrubbing solution 53b. The controller 80
illustratively includes a housing 89 containing processing
electronics 81, such as mounted on a circuit board for example, for
controlling the polymeric amine supply 60 as will be readily
understood by those skilled in the art. Hydrogen sulfide sensors,
including an inlet gas sensor 82a and a discharge gas sensor 82b,
are connected to the processing electronics 81. Accordingly, the
controller 80 controls the polymeric amine supply 60 based upon the
inlet gas sensor 82a and discharge gas sensor 82b.
[0041] The inlet gas sensor 82a includes a sampling tube 83a having
an inlet 84a that is illustratively connected in fluid
communication with the hydrogen sulfide-containing gas flow 22 from
the aerator 18 and into the inlet 43 of the first scrubber tank.
The sampling tube 83a of the inlet gas sensor 82a also
illustratively includes an outlet 85a. A hydrogen sulfide sensing
device 86a is positioned remote from the aerator 18 illustratively
within the controller housing 89, and is connected to the outlet
85a of the sampling tube 83a.
[0042] Similarly, the discharge gas sensor 82b includes a sampling
tube 83b having an inlet 84b connected in fluid communication to
the discharge gas flow 48 from the second scrubber tank 42b. The
sampling tube 83b of the discharge gas sensor 82b also
illustratively includes an outlet 85b. A hydrogen sulfide sensing
device 86b is positioned remote from the second scrubber tank 42b
and within the housing 89, and is connected to the outlet 85b of
the sampling tube 83b.
[0043] A purge pump 88 is provided within the controller housing
89, and is illustratively connected to the processing electronics
81 and the sampling tubes 83a, 83b adjacent the outlets 85a, 85b.
Condensation drain valves 87a, 87b are also illustratively
connected to the processing electronics 81 and the sampling tubes
83a, 83b. The controller 80 periodically operates the purge pump 88
and the condensation drain valves 87a, 87b to drain condensation
from within the sampling tubes 83a, 83b to thereby obtain more
accurate hydrogen sulfide readings as will be appreciated by those
skilled in the art.
[0044] Turning now more particularly to FIG. 4, a second embodiment
of the hydrogen sulfide scrubber 40' is now described. In the
second embodiment, the hydrogen sulfide scrubber 40' comprises a
caustic supply 26' illustratively connected to the first and second
scrubber tanks 42a', 42b'. A switchover valve arrangement 27' for
permitting selective alternate operation using the caustic supply
26' or the polymeric amine compound supply 60' is illustratively
included. More specifically, when use of the polymeric amine supply
60' is desired, valves adjacent the caustic supply 27a', 27b' are
closed to cut off the supply of caustic material. A valve 27d' for
the polymeric amine supply 60' is opened to allow the polymeric
amine 62' to be supplied to the second scrubbing solution 53b'.
Further, a valve on the charging line 27c' is opened to allow
charging of the first scrubbing solution 53a' with a portion of the
second scrubbing solution 53b'.
[0045] When using the caustic supply 26', make-up water is supplied
to both the first and second scrubbing solution circulators 50a',
50b'. The opposite valve configuration is employed to again use the
caustic. The other elements of the second embodiment of the
hydrogen sulfide scrubber 40' are similar to those of the first
embodiment, are identified using prime notation and require no
further discussion herein. The retrofitting and switchover feature
advantageously permits water treatment plant operators to become
familiar and gain experience with the use of the polymeric amine 62
in the water treatment process before making a commitment to retire
existing caustic based equipment.
[0046] Turning now additionally to FIGS. 5 and 6, a third
embodiment of the hydrogen sulfide scrubber 40" and another
advantageous features are now described. The third embodiment of
the hydrogen sulfide scrubber 40" illustratively includes only a
single scrubber tank 42". In accordance with this embodiment, a
single stage of hydrogen sulfide reduction is provided using the
polymeric amine supply 60", along with a mist generator 100 for
generating a scrubber solution mist 101 in the space above the
scrubbing solution 53" in the sump 56" and beneath the scrubber
media 46".
[0047] The mist generator 100" includes a regenerative blower 102"
and a nozzle associated therewith. The regenerative blower
generates a flow from the inlet 104" to the outlet 105". In the
illustrated embodiment, the nozzle is a venturi injection nozzle
103" having a liquid inlet 106" connected to the line 55" from the
circulating pump 58". This nozzle 103" has found to be efficient in
generating the desired scrubbing solution mist 101". The venturi
injector nozzle 103" may of the type as provided by MAZZEI.RTM.
Injector Corporation of Bakersfield, Calif. U.S. Pat. No. 5,863,128
also discloses such injectors, and the entire contents of this
patent are incorporated herein by reference.
[0048] This scrubbing solution mist 101" is believed to further
increase the contact time and area of the hydrogen
sulfide-containing gas with the polymeric amine, and thereby
greatly knock down the hydrogen sulfide and mercaptans.
Accordingly, even for a multi-stage scrubber as described above, it
may be sufficient to provide such a mist generator 100" including
the regenerative blower 102" and associated venturi injector nozzle
103" on only the first or inlet stage. Of course, those of skill in
the art will appreciate that this mist generator 100" may be used
on additional or all other stages as well. The other elements of
the third embodiment of the hydrogen sulfide scrubber 40" are
similar to those of the first and second embodiments, are
identified using double prime notation, and require no further
discussion herein.
[0049] Turning now additionally to the flow chart 90 of FIG. 7, a
method of scrubbing a hydrogen sulfide-containing gas flow 22 from
an aerator 18 in a drinking water treatment system 10 is now
described. From the start (Block 91), hydrogen sulfide-containing
gas flow 22 is received in the first scrubber tank 42a at Block 92.
At Block 93, the first scrubbing solution is circulated into
contact with scrubber media 46a in the first scrubber tank 42a. At
Block 94, gas is discharged from the first scrubbing tank 42a and
received in the second scrubber tank 42b. The second scrubbing
solution 53b is circulated into contact with scrubber media 46b in
the second scrubber tank 42b at Block 95. At Block 96 the polymeric
amine 62 is supplied to the second scrubber solution 53b. The first
scrubber solution 53a is charged with a portion of the second
scrubber solution 53b at Block 97. During this process, hydrogen
sulfide-containing gas 22 is continuously received at Block 92. At
Block 98, the scrubbed gas is discharged from the second scrubber
tank 42b.
[0050] Turning now additionally to the flow chart 110 of FIG. 8 and
again to FIG. 4, a method of retrofitting the hydrogen sulfide
scrubber 40 of the drinking water treatment system 10 from a
caustic supply 26' to the polymeric amine supply 60' is now
described. From the start (Block 111), the caustic supply 26' for
the first and second scrubber tanks 42a', 42b' is disconnected or
shut off by valve arrangement 27' at Block 112. At Block 113, the
polymeric amine supply 60' is connected to the second tank 42b'. A
scrubbing solution charging line 70 is connected between the second
scrubber tank 42b and the first scrubber tank 42a' at Block 114. At
Block 115 the scrubbing solution circulators 50a', 50b' are left
unchanged. The make-up water supply 24a' of the first scrubber tank
42a' is turned off and the make-up water supply 24b' of the second
scrubber tank 42b' is reduced at Block 116. At Block 117, the
hydrogen sulfide sensors 82a', 82b' are installed and the
controller 80' is installed at Block 118. The method is completed
at Block 119.
[0051] Many modifications and other embodiments of the invention
will come to the mind of one skilled in the art having the benefit
of the teachings presented in the foregoing descriptions and the
associated drawings. Therefore, it is to be understood that the
invention is not to be limited to the specific embodiments
disclosed, and that other modifications and embodiments are
intended to be included within the scope of the appended
claims.
* * * * *